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The image on old TVs and film is really a sequence of still shots sent quickly enough to fool our eyes into seeing a continuous stream. Given our flicker-fusion rate, the film needs to be only slightly faster than 60 still images a second to trick our eyes into seeing motion. Dogs, though, have a faster flicker-fusion rate—about 70 or 80 stills per second. When watching film, they can actually detect the individual frames as well as the dark spaces between them. With the recent conversion to entirely digital television broadcasts, though, the flicker-fusion rate is no longer relevant, since digital TV works differently. So dogs can, in theory, watch TV—though it still is not very olfactorily interesting!

B: Why do you think it took researchers so long to truly study the dog?

AH: I think it took scientists a long time to see dogs as cognitively interesting because they reasoned that animals who are closely related to us—like apes and monkeys—were more likely to display behaviors similar to those of humans. As it turns out, in social cognitive tasks such as interpreting others’ gestures, dogs often surpass chimpanzees in performance! Additionally, I suspect that it was felt that dogs were already “known,” because they are so common and familiar to us as pets. What we are discovering is that in some cases, we are correct about what dogs know and understand, and in many cases, our common-sense understanding of dogs is not quite right.

B: A lot of your research involves dog play. Why is play so important?

AH: Play is a terrific venue in which to see dogs’ fast-paced, coordinated behavior; they are highly skilled players. As many dog owners may know, most bouts of play begin with a play signal, such as the familiar “play bow,” in which one dog bends down on his front legs, holding his rump high and his tail up and wagging. Another signal is the “exaggerated approach,” in which one dog lopes toward another dog, often with an extra-bouncy stride. These signals are considered requests to play, or announcements of an interest in playing. It appears to be important to play signal before starting to play, since play involves behavior that would be considered aggressive—biting, mounting, bumping—in another context.

When I looked at play sequences in very slow motion, what I was able to see was that dogs were very good at getting the attention of their hoped-for playmates before play signaling. And they seemed to know what kind of attention-getter would work in different situations: a more forceful attention-getter when the other dog is distracted, a mild one when the dog is standing idly. With humans, a person might need to shout to get the attention of someone talking to someone else; similarly, we don’t need to barge into someone standing right in front of us in order to get his attention. Dogs seem to know that. And then, only after getting the other dogs’ attention, did they signal an interest in playing.

B: Dogs of the same “breed type,” like herders, seem to enjoy playing together and appear to have different styles of play than other breed types. For instance, they use the “eye,” and play “who winks first gets to be chased.” Have you studied behavioral traits in breeds and how they are expressed during play?

AH: I find it extremely interesting that breeds often gravitate to other members of their breed to play. Indeed, it seems that even similar-looking mixed-breeds often play together. Some of that could be explained by their owners’ interest in the familiar-looking or -acting dog (if owners loiter together, it gives the dogs more time to get acquainted). But most of it presumably comes from the dogs’ mutual recognition of characteristic behaviors in one another: the way the other dog solicits play, how he uses his tail and, as you suggest, even showing “eye” or other breed-typical behaviors. My own research did not control for breed, and I don’t know of any other studies that have specifically identified whether or not certain behaviors are more likely during play among members of one breed than play among members of another. It’s ripe for the investigating!

B: It was interesting that you said that long-time or close playmates can exchange shorthand signals with each other. How can we learn to read our dog’s shorthand?